Two issues: NAT and dynamic addresses. NAT: blocking an iot address may be blocking grandma's whole network (or her whole apartment complex's network), and the

Two issues: NAT and dynamic addresses. NAT: blocking an iot address may be blocking grandma's whole network (or her whole apartment complex's network), and the ISP doesn't want that support call. Dynamic addresses: depending on the ISP, the IP could change quite frequently (daily), so keeping the list up to date to avoid collateral damage to the unlucky recipient of the blacklisted IP is very difficult.